The invention relates to a structure of push switch device and, more particularly, to a structure that can enhance the service life of the push switch device.
FIG. 1 is an exploded view that schematically illustrates a structure of push switch device disclosed in a previous U.S. patent application Ser. No. 09/740,997, now U.S. Pat. No. 6,441,331, filed by the same applicant as the present application. As illustrated, the push switch device of the prior art, used to signal connection or output, comprises a body on which two terminals are mounted. A first resilient unit is further arranged within the body, below a push unit. A cover further closes the cover. Under the application of an external pressure therein, the push unit drives a displacement of the second resilient unit to push on the first resilient unit. Under the application of an external pressure thereon, the push unit drives a displacement of the second resilient unit to push on the first resilient unit. Under this down pushing action, the first resilient unit establishes electrical contact with two terminals, thereby establishing an electrical output. When no pressure is exerted on the push unit, the first and second resilient units exert a reverse resilient force that lets the push unit recover its initial position.
Although the above structure is simpler than traditional structures of push switch device and has less contact points, which reduces the electric resistance and prevents signal deterioration, but improvements still need to be accomplished with respect to the disposition of the resilient units.
Therefore, the same applicant has disclosed another structure of push switch device in another application, as also illustrated in FIG. 2. As shown in FIG. 2, this structure includes a body, two terminals disposed on the body, a resilient unit arranged within the body, a push unit arranged above the resilient unit within the body, and a cover closing over the body. The above structure, suitable for signal connection and output, is characterized in that the resilient unit is comprised of an actuating portion that extends into support portions at two ends, these support portions being disposed within the body. Furthermore, the push unit is provided with a recess to receive the actuating portion of the resilient unit. With this disposition, when the push unit is pushed down, an inner radius of the actuating portion contracts, which causes the support portions to be pushed down and electrically contact with the terminals, thereby establishing a signal connection. When no external pressure is exerted on the push unit, the resilient unit exerts a reverse resilient force that let the push unit recover its initial position.
The second structure of push switch device as illustrated in FIG. 2 provides a simpler and more achieved construction in comparison with the first structure as illustrated in FIG. 1. However, both structures still have the following disadvantages. The feeling of push contact the user have when pushing and the accompanying sound are produced via the contact between a recess of the push unit and the corresponding second resilient unit and protruding point formed on the cover. The push unit being usually made of plastics and the cover of metal, a pushing action on the push unit therefore easily causes the protruding point of the metallic cover to scrape the plastics-made push unit. With numerous pushing actions, the scrape on the push unit becomes increasingly deeper until it is deeper than the length of the protruding point of the cover. As a result, no push contact feeling and corresponding sound are therefore produced, which negatively reduces the service life of these elements.
Accordingly, it is therefore a principal object of the invention to provide a structure of switch device that can overcome the above problems of push unit wear off due to scraping effects for producing a push contact feeling and corresponding sound. Thereby, the service life of the switch device and its quality are enhanced.
To attain the above and other objectives, a push switch device of the invention comprises a body including a set of terminals, a periphery of the body being further provided with a first assembly element. A cover includes a second assembly element that assembles with the first assembly element of the body in a manner to close the body. An inner side of the cover is provided with a second resilient unit on which is formed a stopper portion. A push unit is further formed through the body, the push unit being provided with a stop controller pad made of an abrasion-resistant material that faces the stopper portion. A first resilient unit is further placed below the push unit.
With the above disposition, when a pressure is exerted on the push unit, the stop controller pad pushes on the stopper portion that moves outwardly. Thereby a wearing damageable contact of the stopper portion with the push unit is prevented, meanwhile the first and second assembly elements enable a rapid and simple assembly of the body with the cover.
To provide a further understanding of the invention, the following detailed description illustrates embodiments and examples of the invention, this detailed description being provided only for illustration of the invention.